1. Field of the Invention
This invention relates to a surgical stapler for suturing tissues in a surgical operation with square U-shaped staples, and more particularly to a surgical suturing stapler capable of being readily loaded with staples by use of a detachable staple cartridge.
2. Description of the Prior Art
The inventor of this invention has formerly proposed surgical suturing staplers for inserting square U-shaped staples into a bodily part to stitch a wound or the like and arrest hemorrhage. (Japanese Patent Public Discl. No. SHO 63(1988)-270040(A) and Japanese U.M. Pub. Discl. No. HEI 1(1990)-62810(A))
The prior art surgical staplers including the staplers proposed by the inventor as noted above can discharge a number of U-shaped staples in one lot into a bodily part as illustrated in FIGS. 1 and 2. The stapler of this type comprises a pair of jaws 1a, 1b pivotally supported by an axial pin a1, a pair of handles 2a, 2b having tip portions rotatably connected to the jaws 1a, 1b through axial pins a2, a3 and pivotally supported by an axial pin a4, and a staple magazine 3. As shown in FIG. 2, two parallel rows of staple chambers 4 in which the staples (S) are loaded are formed in the staple magazine 3.
The upper jaw 1a has extruding pieces 5 to be plunged into the staple chambers 4 in the staple magazine 3 to push the staples (S) out of the staple chambers 4 toward the lower jaw 1b. The lower jaw 1b is provided in its upper surface with anvil grooves 6 opposite to the staple chambers 4 in the staple magazine so as to bend inwardly the legs of each staple (S) being thrust thereinto.
A bodily part such as the edges of a wound in a surgical operation can be sutured with the staples (S) merely by gripping the handles 2a, 2b while putting the bodily part between the upper and lower jaws 1a and 1b. By gripping the handles 2a, 2b, the upper and lower jaws 1a, 1b are rotated around the axial pin a1 and closed to force the staples out of the staple chambers 4. The staples thus forced out are pressed against the lower jaw 1b to cause the legs of the staples to be thrust into the anvil grooves 6 and bent inwardly. Thus, the tissues are kept in a state pressed with the staples so as to arrest hemorrhage.
The surgical stapler noted above provides advantageous suturing of the tissues of a living body, as even a large incision part can be easily stitched with a number of staples in one operation. This stapler has been found a big help in a surgical operation requiring prompt treatment, but is disadvantageous in that the work of being loaded with the staples (S) turns out to be a very troublesome chore in a surgical operation. That is, the staples (S) must be inserted one by one into the staple chambers 4 formed in the staple magazine 3 by hand while the upper and lower jaws 1a, 1b are opened as wide as possible. This work requires much time and labor and proves to be troublesome, so that it is substantially impossible to load the staple magazine with the staples during an operation.
Furthermore, the conventional surgical stapler entails problems such as difficulty in visually discerning whether the staples are infallibly placed in all the staple chambers 4 of the staple magazine. There is a possibility that a staple may fall out of the staple chamber in the magazine accidentally, suffering a disadvantage that a wound or other possible tissues would be incompletely sutured due to the falling out of the staple. For instance, when the staple (S') as shown in FIG. 2 fails to be charged in or falls out of the staple chamber, the part (d) indicated in the drawing cannot provide the effects of suturing tissues and arresting hemorrhage.
In the surgical stapler of this type, the staple is retained inside the staple chamber 4 by frictional force produced by the inner surrounding surface of the staple chamber. However, the friction force by which the staple is retained would gradually decrease during the course of prolonged service, and therefore, the staple retained would easily fall out of the staple chamber with slight shock or other possible external force.
The anvil groove 6 formed in the lower jaw 1b of the conventional surgical stapler has a bottom surface 6a shaped in a substantial .omega. as shown in FIG. 3. The staple being thrust into the anvil groove is bent inwardly along the bottom surface 6a of the anvil groove 6 with the pointed ends of the legs being curved upwardly, as indicated by imaginary lines in the drawing. Namely, the staple is bent in a general B-shape. Therefore, the grasping force at the central portion of the bent staple becomes weaker, so that the effect of arresting hemorrhage at that portion would be reduced. Thus, the conventional stapler entails disadvantages in that the staples cannot be readily loaded nor reliably retained within the staple chambers in the staple magazine, and the legs of the staples cannot be bent suitably, thereby suturing tissues incompletely.